The present invention relates to components and systems adapted for variable absorption of impact energy, and more specifically relates to an energy absorber for use on front and rear bumpers of vehicles and in the passenger compartment of vehicles, such as on the interior surface of structural roof pillars, headliners, interior door panels, instrument panels, and other places where impact absorption is an important feature of the component. It is contemplated that a scope of the present invention is not limited to automobiles, nor to only passenger vehicles.
It is difficult to reduce vehicle size while also maintaining a comfortable amount of internal space for passengers and while also maintaining passenger safety. Specifically, the packaging space within modern vehicle passenger compartments is becoming more severe (i.e., more critical) as vehicles are becoming smaller, since the passenger compartment within the vehicles must remain sufficient in size for good passenger comfort and movement. The net result is that there is less space between the outside of the vehicle and the inside of the vehicle (i.e., the passenger compartment) for the vehicle's body structure. For example, the structural pillars of a vehicle must be sufficient in size to structurally support the vehicle's roof, but must be as small as possible in cross section in order to maximize a size of the passenger compartment.
One way of increasing passenger safety (i.e., reducing passenger injury during a vehicle crash) is to cover rigid components (i.e., components that might cause injury to a passenger during a vehicle crash) with an energy-absorbing trim component or an energy-absorbing layer under the trim component. However, such components and arrangements tend to be thicker (in order to provide a longer “crush stroke”), which results in a greater loss of the internal space in the vehicle's passenger compartment. Obviously, components can also be made stiffer so that they provide increased energy absorption (i.e., greater deceleration) during a vehicle crash, but an upper level of stiffness is quickly reached since higher levels of stiffness can cause the component itself to create injury to the passenger.
More specifically, one objective of safety devices within the passenger compartment of an automobile or other mode of transportation is to reduce the severity of injury to the occupant when involved in high-speed collisions. The main approach is to decelerate the occupant during the impact at a slow enough rate that major injury, broken bones, internal injuries, trauma to the head, etc. will not cause permanent debilitation, extensive reconstruction and therapy, or death. Several types of energy management strategies are taken, usually in combination. These are: constraints, such as seat belts, active systems, which sense the severity of an impact and deploy a cushioning device or initiate an avoidance mechanism and passive systems, such as air bags and other static energy-absorbing structures and materials. With the passive systems, there is usually a conflict in the ability to reduce the deceleration rate (minimize loads and G forces on the occupant) and the desire to maintain the minimum amount of space that a structure requires (i.e., smaller parts provide smaller impact strokes). Physics dictates that the kinetic energy involved in the deceleration of an occupant is equivalent to the sum of the load exerted on the occupant times the amount of displacement into the structure. Thus if it is desired to keep the loads/acceleration low, it requires more available crush space, which is often in conflict with the desire to maximize occupant compartment space, improve visibility and comfort, etc. In order to minimize the space, significant efforts are made to create a structure that can absorb the energy efficiently, that is to keep the load/acceleration as constant as possible, just below the desired limits until all the energy is absorbed. Many different types of structures have been employed to achieve this end, such as expanded or foamed materials, injection-molded ribbed structures, various shaped structures from numerous types of materials and manufacturing methods. Each of these structures is limited to the laws of physics described above. The present invention involves bringing elements of the active and passive systems together in a way that changes the limits of the physics during an impact event while not encroaching on the occupant space during normal operating conditions.
An improved energy absorber is desired for providing optimal energy absorption, including a longer crush stroke, without subtracting from the interior passenger compartment of vehicles. In addition to “gross” or total impact energy absorption, it is also desirable to provide a system that not only passively distributes energy absorption during an impact, but further that actively laterally distributes energy during an impact.
Still further, it is desirable to provide a system that is responsive to vehicle crashes, and that actively adjusts to provide optimal impact-absorbing characteristics for particular types of impacts/vehicle crashes. For example, a first energy absorbing profile (i.e., energy absorption versus impact stroke curve) may be most appropriate for a low-speed impact (such as to minimize vehicle damage), a second energy-absorbing profile may be more appropriate for low-speed pedestrian impact (such as to minimize injury to the pedestrian), a third energy-absorbing profile may be more appropriate for high-speed impact against a fixed barrier (so as to minimize injury to a vehicle passenger from forward impact), a fourth energy-absorbing profile may be more appropriate for a side-of-vehicle impact (so as to minimize injury to a vehicle passenger from side forces), etc.
In short an improved total and variable energy management system is desired that optimizes pedestrian and occupant safety while minimizing vehicle damage. In addition, it is desirable to provide an energy absorption system that does not require expensive tooling with long lead times. Further, it is desirable to provide an energy absorption system that can be readily modified and used across multiple vehicle makes and models. Still further, it is desirable to provide an energy management system that is responsive to a type of impact, and that extends outward in response to a particular signal from a pre-crash or post-impact sensor.
Thus, a system is desired having the aforementioned advantages and solving the aforementioned problems.